Policy Exchange has commissioned a report recommending a new waterborne Tube Line across the River Thames stretching from Putney to Woolwich – see this PDF. The report includes contributions from Justine Greening MP, Zac Goldsmith, Andrew Gilligan, Steven Norris and Boris Johnson's Adviser on Transport, Kulveer Ranger.
The report claims that in less than three years for an initial costing of £30million a fast and frequent boat service can provide an alternative commuting option for Londoners. The proposed revamped high-speed boat service will be both environmentally friendlier and more cost-effective than other transport infrastructure projects. New piers will be constructed in the Docklands and the Thames Gateway and the existing boat service will be extended as far as Putney in order to cover more of West London. There will be a total of 20 piers along the Thames and existing piers will be modernised. The service will be fully integrated with the Tube. If delivered it is hoped that an estimated 12million journeys can be achieved on the high-speed boat service by 2026 which will ease the congestion on the Tube network and London's roads.